Abstract

The effects on egg production of supplementing Moringa oleifera
leaf meal and molasses to grain sorghum based diets for commercial layer
chickens was studied in a 2x3 factorial design for ten weeks. The study used
high (HT) and low (LT) tannin varieties of sorghum and three supplement
strategies of: none, molasses (Mo) or Moringa leaf meal (ML).

Egg weight was not influenced by tannin level. Daily feed intake was higher,
feed conversion poorer and egg laying percentage and egg mass production
lower in HT than in LT diets. Supplementation with molasses depressed, while
supplementation with Moringa leaf meal improved, egg production. Final sugar
cane molasses is not recommended as additive to sorghum based diets as it
may depress egg production and impair feed conversion. Moringa oleifera
leaf meal appears to improve egg production on sorghum based diets and may
reduce the expense of using costly synthetic amino acids. Its utilization as
an additive in sorghum-based diets is highly recommended.

Key words: agroforestry, egg production, tannin, Tanzania

Introduction

Sorghum (Sorghum bicolor) is well adapted to arid and semi-arid
regions and could be used as an alternative to maize due to its high energy
content and its chemical composition is similar to maize, except for the
deficiency in lysine, methionine, and threonine (USDA 2009 and Mutayoba et
al 2011). Sorghum ranks the fifth as the most produced crop worldwide (NRC
1996). The use of sorghum in poultry diets is limited probably due to the
presence of tannin in some of the varieties (Dykes and Rooney 2006; Medugu
et al 2010). The Proanthocyanidins (condensed tannins) consisting of
oligomers and polymers of flavan-3-ol units are the most widely distributed
type of tannins in plants (Waterman and Mole 1994). In rare
cases,Proanthocyanidins comprising 3-deoxy subunits also exist particularly
in sorghum and maize. Studies have shown that the presence of these
compounds at more than 1% in the diet could depress egg production
performance in layers (Potter et al 1967; Armstrong et al 1973). In addition
excessive tannin consumption can lead to a reduction in feed intake, egg
weight, laying rate and poor feed conversion ratio (Sell and Featherston
1983; Kyarisiima 2004). Tannin is thought to impair digestion and absorption
of nutrients (Lasheras et al 1980a, b), alter nutrient partitioning and
tissue composition (Cherian et al 2002; Du et al 2002), and cause cell
degeneration in the liver and kidneys (Harvey and McAllan 1992).

Various studies to improve nutritional quality and utilization of
high-tannin grain sorghum using physical and chemical treatment (Mitaru et
al 1983 and Elkin et al 1990) and dietary nutrient enrichment (Nyachoti et
al., 1997 and Kumarl et al 2005) have been carried out. Furthermore,
attempts to increase dietary protein and energy levels using common
ingredients in high tannin grain sorghum based diets have also been done
(Sell et al 1983; Pour-Reza and Edriss 1997). Both nutritional strategies
were found to improve partially performance in laying birds. It is
anticipated that the use of Moringa oleifera leaf meal and molasses
that are readily available and cheap in tropical countries could alleviate
the negative effects of tannins on egg production performance since they
contain essential nutrients with negligible anti-nutritional factors (Alikwe
and Omotosho 2003; Aye and Adegun 2003). However, there is limited
information on the effect of using Moringa leaf meal and molasses in high
tannin grain sorghum based diets on egg production. Thus, the objective of
this study was to find out if supplementation of Moringa oleifera
leaf meal or molasses to high tannin grain sorghum based diets could
alleviate the undesirable effects of tannins and improve laying performance.

Materials and methods

Feed ingredients and experimental diets

The study was conducted at Sokoine University of Agriculture (SUA) at the
Poultry Unit in the Department of Animal Science and Production (DASP) in
Morogoro, Tanzania. Moringa oleifera leaves were harvested within
SUA compound, air dried under a shed to maintain their greenish colour,
ground with hammer mill to produce Moringa leaf mal (ML). Grain sorghum
varieties were collected from the local markets, ground with hammer mill to
pass through a 2mm sieve. Molasses was obtained from Mtibwa sugar processing
company. The methods of Association of Official Analytical Chemists (AOAC
1990) were used to determine proximate composition, minerals and ash of the
feed ingredients and experimental diets. Metabolizable Energy (ME/ kcal/kg)
content of feed ingredients and experimental diets were estimated by
prediction equations expressed by NRC (1994). MOLM, ME/Kgcal/kg was
estimated by prediction equation established by Carpenter and Clegg (1956).
Condensed tannins in GSV and MOLM were determined using butanol/HCL method
as described by Nitao et al (2001). All ME n values were
converted into MJ/kg DM. All diets were formulated to meet or exceed the
nutrient requirements recommended by NRC (1994) (Table 1) for layer
chickens. The inclusion of the sorghum was fixed at 55% of the DM.

Experimental design and dietary treatments

Experimental procedure

Two hundred and seventy (270) commercial Bovan brown hybrid layer chickens
at 20th week of age were randomly allocated to the dietary
treatments. Each dietary treatment had 45 birds subdivided into three
replicates of 15 birds each. The birds were housed in deep litter pens. The
birds were provided with the experimental diets from the 20th to
30th week of age. Prior to the commencement of the experiment,
each bird was weighed individually to obtain the initial body weight and at
the end of experimental period to get final weight. Birds were group fed in
each replicate. The experimental diets supplied to the birds were weighed
daily and were given to the birds every morning at 8.00A.M. The amount of
feed offered daily was approximately 20 percent above the expected intake.
The remaining feed (residue) was also weighed daily before supplying fresh
feed. Feed intake per bird was calculated by subtracting the leftovers from
feed and was divided by the number of birds. Eggs were collected and
recorded on a daily basis. Eggs were weighed daily using sensitive digital
weighing scale. Daily laying percentage was calculated as the number of eggs
produced over a period of time by dividing the number birds x 100. Average
egg weight was calculated as total egg weight by dividing the number of
recorded eggs. Daily egg mass was calculated as average egg weight
multiplying by daily laying percentage. The daily feed intake (g) over daily
egg mass (g) was used to calculate the feed conversion ratio (FCR).

Data analysis

All data collected on egg production performance parameters for GVS and SPS
was analyzed in accordance with the 2x3 factorial designs of two GSV in
combination with three SPS using General Linear Model procedure of SAS
software version 9.1 for windows (2007). Values were considered significant
at (P ≤ 0.05). The Least Square Difference was used to compare
means of each variable. The analytical model for studied parameters were as
follows: Yijk = μ + Vi + Sj+ (VS)ij+
eijk

Results

Effect of tannin

The egg weight (EWT) values did not differ between HT and LT diets (Table
2). The laying percentage (DLP) and egg mass production (EMP) were lower by
32.2 and 27.9% respectively in HT compared to LT dietary groups. The daily
feed intake (DFI)) was higher by 7.2% and the feed conversion poorer by 59%
in HT compared to LT dietary groups.

Effect of supplement

The DLP value decreased with molasses by 21.1% but increased with Moringa by
8.7% (Table 3). Similarly, the EMP value was decreased by molasses by 19.9%
but was increased by MOL by 7.24%. The DFI increased by 2.63% with molasses
but did not change with Moringa, compared to the control. The FCR value did
not differ among supplements. There was an interaction between tannin diets
and supplements (Table 4). Molasses had a negative effect on feed conversion
when it was added to the low tannin diets but had no effect in the high
tannin diets.

abcMeans in the same row with different
superscripts are different (P ≤ 0.05);

Discussion

The lower DLP in HT compared to LTdietary groups concurs with other research
reports (Faquinello et al 2004; Kyarisiima 2004). These findings were
attributed to the negative effects of tannins on utilization and
digestibility of nutrients such as protein and amino acids responsible for
egg formation (Hassan et al 2003; Ravindran et al 2006). These results
support previous studies that tannin levels between 1.5% and 3% may depress
egg production (Ali and Mahmood 2003). According to Potter and Fuller
(1968), HT based diets have a depressive effect on DLP and its use should be
accompanied with supplementation of proteins and amino acids particularly
methionine and choline which donate a methyl group that combines with
tannins and render them ineffective.

The influence of tannin level on feed intake in layers is inconsistent in
the literature. The higher value in HT compared to LT dietary group agrees
with other research reports (Nyakoti and Atkinson 1995; Nyakoti et al 1997).
These findings are associated with the compensatory mechanism of birds to
increase intake due to the lower energy concentration of the high tannin
diet (Cherian et al 2002; Du et al 2002). Therefore, these results suggest
the use of HT sorghum in layer diets is not economical and should be
accompanied with supplementation with more readily available energy sources.
However, these results disagree with other researchers who reported a
decrease in feed intake in HT diets (Attia 1998; Ali and Mahmood 2003).

The influence of tannin on egg weight is variable. Malik and Queensberry
(1963) and Armanious et al (1973) reported a decrease in egg weight when
maize replaced sorghum in laying hen diets. However, our findings suggest
that tannins up to 2.6% DM in the diet have no detrimental effect on egg
weight. These findings are consistent with other research reports (Ambulla
et al 2003; Imik 2009; Kwari et al 2011).

The lower egg mass values noted in HT compared to LT dietary groups compares
well with other research reports (Armonious et al 1973; Faquinello et al
2004; Kyarisiima 2004). These results suggest that tannins have a
detrimental effect on egg mass and could be uneconomical particularly where
eggs are graded.

The poorer feed conversion values noted in HT compared to LT dietary groups
may be attributed to the higher feed intake and lower egg mass, due to
negative effect of tannins.

The decrease of egg laying percentage in diets supplemented with molasses
may be attributed tothe low metabolizable energy and almost complete absence
of amino acids reported in final sugar cane molasses (Ly 1979, 1990).
However, these results are inconsistent with previous research reports
(Damron et al 1980; Rahman et al 1991; Valdivie 2003) which may be due to
differences in type of molasses and the basal diet used (Ly 1990). The
increasein egg laying percentage due to Moringa leaf meal was probably due
to the effects of the higher protein availability in Moringa (Sikka and
Johari 1979; Makker and Becker 1997). These finding suggest utilization of
moringa leaf meal as additive in sorghum based diets for layer chickens can
improve laying rate and minimize the need for supplementary synthetic amino
acids. However, there are also conflicting reports on the effect of Moringa
leaf meal on egg production (Abou-Elezz et al 2011).

Conclusion

High tannin grain sorghum as a source of energy in layer diets depresses
egg laying rate, egg mass production and feed conversion

Moringa oleifera leaf meal is a suitable additive to grain sorghum based diets for layer
chickens as it improves egg production and could eventually reduce the
expenses of using synthetic amino acids.

Final sugar cane molasses is not an appropriate additive to grain sorghum
based diet for layer chickens as its use depresses egg production and feed
conversion

Acknowledgement

The authors would like to knowledge the Tanzanian Government through the
Ministry of Livestock and Fisheries for financial support for this research
project.